Systemic lupus erythematosus-specific CD14⁺IFITM3⁺ monocyte: Implications for disease activity and progression

Interferon-inducible transmembrane (IFITM) family members (IFITM1, IFITM2, IFITM3) are extensively expressed in T cells and are involved in adaptive immunity. However, little is known about the expression of IFITM1, IFITM2 and IFITM3 in monocytes and their roles in systemic lupus erythematosus (SLE). Our study has shown that the expression of IFITM1, IFITM2, and IFITM3 in peripheral blood mononuclear cells (PBMCs) of SLE patients was dysregulated, and the expression of IFITM3 in SLE was significantly higher than that of healthy controls. Besides, the percentage of CD14⁺IFITM3⁺ monocyte in the peripheral circulation of SLE patients was significantly increased, which was significantly correlated with inflammatory and immune indexes (ESR, CRP, PLT, urine-β₂M, and urine mALB) of SLE. Most importantly, the percentage of CD14⁺IFITM3⁺ monocyte was positively associated with the SLEDAI score, suggesting it predictive role in SLE disease activity. In summary, we have found that IFITM3 may serve as a SLE-specific marker and the dysregulation of CD14⁺IFITM3⁺ monocyte may affect the disease activity and progression of SLE.